Mark Scheme (Results) January 2015

Transcription

1 Mark Scheme (Results) January 205 Pearson Edexcel International GCSE in Biology (4BI0) Paper B Pearson Edexcel Certificate GCSE in Biology (KBI0) Paper B

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3 General Marking Guidance All candidates must receive the same treatment. Examiners must mark the first candidate in exactly the same way as they mark the last. Mark schemes should be applied positively. Candidates must be rewarded for what they have shown they can do rather than penalised for omissions. Examiners should mark according to the mark scheme not according to their perception of where the grade boundaries may lie. There is no ceiling on achievement. All marks on the mark scheme should be used appropriately. All the marks on the mark scheme are designed to be awarded. Examiners should always award full marks if deserved, i.e. if the answer matches the mark scheme. Examiners should also be prepared to award zero marks if the candidate s response is not worthy of credit according to the mark scheme. Where some judgement is required, mark schemes will provide the principles by which marks will be awarded and exemplification may be limited. When examiners are in doubt regarding the application of the mark scheme to a candidate s response, the team leader must be consulted. Crossed out work should be marked UNLESS the candidate has replaced it with an alternative response.

4 (a) 5 Effect Name of hormone Source converts glucose to glycogen stimulates male secondary sexual characteristics increases permeability of the collecting duct (insulin) testosterone; ADH; (pancreas) (testis) hypothalamus / pituitary; repairs uterus lining oestrogen; ovary; Allow reasonable spellings

5 (b). soluble / dissolves; Ignore small 2 2. osmotic effect / eq; (c) X; Total 8 marks

6 2 (a) easier to see / no need to stain / contrast / cytoplasm is red / eq; (b) (i). movement of water; 2. from dilute to more concentrated solution / eq; 2 (ii) 3. through partially permeable membrane / eq; (in distilled water). water into cells; 2. outside solution/distilled water more dilute / down concentration gradient / eq; 3. cell membrane against cell wall / eq; 4. turgid; (allow converse in salt solution for each point). water leaves cell; 2. outside solution/distilled water less concentrated / eq; 3. cell membrane shrinks away from cell wall /eq 4. plasmolysed / flaccid; 4 (c). water into red blood cell / eq; 2. cells burst / haemolysis / eq; 3. no cell wall; 2 Total 9 marks

7 3(a) (i) safety glasses / wear gloves ; Ignore lab coat / tie hair back / eq (ii) / eleven; (b) (i) remove starch / solution from surface of syringe / eq; Ignore get into syringe (ii) mix contents / mix amylase and starch / eq; Mix alone = 0 Allow enzyme and starch (iii) keep at correct temperature / keep temperature constant / eq; Ignore fair test

8 (c) (i). volume / concentration of amylase; 2. volume / concentration of starch; 3. volume / concentration of iodine / drops of iodine; 4. volume / concentration of mixture; Allow amount only once 2 (ii) temperature; Ignore time (d). 6 minutes / between 5 and 6 minutes / eq; 2. iodine stays yellow / orange / brown / iodine stays same colour / colourless / not blue black; 3. no starch present; 4. digested/broken down ; Reject 6-7 mins 3 Question (e)(i). fewer wells with blue black colour / more wells yellow / orange / brown / colourless / eq; 2. starch digested sooner / quicker / reaction completed sooner / eq; 2 (ii). enzymes work faster at 40 0 C / ref to optimum / eq; 2. more (kinetic) energy / molecules move faster / eq; 3. more collisions / more enzyme substrate complexes /eq; Ignore ref to denature 2 Total 5 marks

9 4 ( (a) (b)(i). narrower lumen / eq; 2. thicker wall; 3. more muscle / stronger muscle / eq; 4. more elastic; 5. no valves; Ignore blood flow Allow converse 2 4 vena cava Name of blood vessel Letter L or N aorta C; pulmonary vein B; hepatic artery D; renal vein I; Reject B and D and B or D (b)(ii) Contents of blood vessel Letter of blood vessel 3 contains the most glucose after a meal J; contains the least urea I; contains the least oxygen M; Total 9 marks

10 5. high humidity decreases rate; One mark for condition and change 2. reduced concentration gradient / eq; in transpiration second mark for explanation of change 3. high wind increases rate ; 4. increased concentration gradient / eq; Allow converse throughout 5 5. high temperature increases rate ; 6. more (kinetic) energy / more evaporation / eq; 7. high light increases rate ; 8. stomata open / eq; Total 5 marks

11 6 (a). lower production / fewer fruit / less growth / eq; 2. (fewer) chloroplasts / less chlorophyll; 3. (less) photosynthesis; 4. (less) carbohydrate / glucose / starch; 3 (b) (i). variation; 2. mutation; 3. rare / random: 4. survive / not killed; 5. reproduce / mates; 6. pass on gene / allele / eq; 4. Ignore resist 6. Ignore characteristic 4 (ii) inside leaf / not reach all parts / eq; (c) biological; (d). no sperm / less reproduction / less breeding / eq; 2. fewer eggs/females fertilised / fewer larvae; 3. sterile male compete for resources / mates; 2

12 Answer Notes Marks (e) C plus pheromone/smell and minus pheromone/smell / traps in field / no traps / eq; 6 O same species of insect/males (trapped) / same species/size of crop / eq; R several traps / repeat / many fields; M count trapped / measure damage / measure yield / eq; M2 time period stated; S and S2 same temperature / light / water / time of year / location/size of field / of plants / size of trap / eq;; Total 7 marks

13 7(a). broken down / digested; Ignore eaten 2 2. bacteria / fungi / microorganisms / saphrophytes / eq; (b). (dead) plants / humus then earthworms then birds; Earthworms in middle = 2 2. arrows correct; (c) (i) 20; (ii) C; (iii) (yes) not enough repeats / may be anomalous / eq; Ignore not enough soil Total 7 marks

14 8 (a) 5 Large food molecule Enzyme involved in digestion Small food molecule produced starch amylase glucose / maltose; Ignore simple sugars protein; protease amino acids / polypeptides / peptides; lipid lipase; fatty acids / glycerol; (b). large surface area / microvilli; 2. thin / short diffusion distance / eq; Ignore many villi / long villi 3 3. blood / capillaries / eq; 4. permeable; 5. lacteal; Total 8 marks

15 9(a). water; 2 2. minerals / ions / salts / named mineral ion / eq; Ignore nutrients Allow 2 marks for 2 named minerals; (b). shape; Palisade cell labelled = max 4 5 Then max 4 from: 2. cell wall; 3. cell membrane; 4. cytoplasm; 5. nucleus; 6. vacuole; Total 7 marks

16 0(a) (i) (ii) 47; male; (b). has more than 46 / has extra chromosome / trisomy; Ignore 47 alone 2 2. (which is) sex chromosome / Y / eq; Has an extra sex chromosome =2 (c) (i) meiosis; (ii). failure of chromosomes to separate / eq; 2 2. (gamete) has an extra chromosome / YY; 3. normal egg/gamete fertilised by abnormal sperm/gamete; Total 7 marks

17 (a) P mm Mm; 4 G m M m; O Mm mm; Ph Marfan / eq unaffected; G. Clear separation of gametes Ph. Allow half Marfan and half unaffected even if not linked to genotypes Allow max from Punnett square Allow 3 max for TE Allow other symbols (b) (i) some people do not have obvious symptoms / some people with symtoms/long fingers/tall do not have condition / heart problems/eyesight problems may have other causes / eq; 2 (ii). look at parents / family history; 2. genetic test / analyse DNA / eq; 3. look for combination of symptoms / look for tall and eyesight / eq; 3. Allow any 2 symptoms

18 (c). condition present in offspring but not in parents; 2. it skips generations / eq; 3. carriers (present); 3 Total 0 marks

19 2 environment; 8 population; community; quadrat; random / different; average / mean; reliability; anomalous / unusual / odd ; Total 8 marks

20 3(a). explants; Max 5 (b) 2. small pieces of tissue / small pieces of plant / eq; 3. agar / jelly; 4. contains nutrients / amino acids / glucose; 5. plant hormones / named hormone / eq; 6. minerals / named mineral; 7. sterile; 8. control light; 9. control humidity;. quick / eq; 2. many produced; 3. any time of year; 4. no genetic variation / genetically identical / produce clones; Allow converse Max 2 Total 7 marks

21 4 3 Structure bacteria Organism fungi viruses If no X s and all in correct places allow Max 2 cell wall ; nucleus ; chloroplast ( ) ; Total 3 marks

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